Heat transfer in a vessel-tubes array with a rotating baffle: A rotating frame modeling approach

Abstract

Conveying heat from one medium to another is more critical when merging these media is banned. Thus, the media should flow individually in separate pipes. This paper explores the exchange of heat between tube bundles enclosed in a circular vessel with a rotating frame. The rotating frame serves to modulate the natural convection to mixed convection. The hot and cold tubes are distributed peripherally while the rotor is centered in the insulated vessel. The study focused on the configuration of the tubes, namely their number, size (r*), and radial position (e*), and how these parameters act with various Rayleigh numbers (Ra = 103 - 105) and rotational speeds (ω* = 0 - 400). The time-dependent equations are discretized and solved using the finite element method with rotating meshes. The outcomes indicate that the augmentation of Nusselt number with the rotational speed and Rayleigh number relies significantly on the radial position, the size as well as the number of hot tubes. The Nusselt number increases by 74.59 % and 9.57 % for Ra = 105 and 103, respectively, when the rotational speed is elevated from 0 to 200, whereas it increases by 308 % when the tube size is reduced from r* = 0.05 to r* = 0.01 at ω* = 200. It is deduced that the size of the tube is the supreme parameter affecting the Nusselt number.

Keywords

• Heat transfer enhancement
• Rotating frame
• Mixer
• Heat exchanger
• Rotating mesh